[v26.x backport] doc: promote Alpine Linux to tier 2 support

[MikeMcC399]

Backports #63737 to v26.x

kernel >= 6.12, musl >= 1.2.5 updated to align with lowest supported version Alpine Linux 3.21
see https://alpinelinux.org/releases/
see https://alpinelinux.org/posts/Alpine-3.21.0-released.html

Alpine 3.22 listed as example version

PR-URL: #63737
Reviewed-By: Matteo Collina matteo.collina@gmail.com
Reviewed-By: Rafael Gonzaga rafael.nunu@hotmail.com
Reviewed-By: Robert Nagy ronagy@icloud.com
Reviewed-By: Chengzhong Wu legendecas@gmail.com
Reviewed-By: Ruy Adorno ruy@vlt.sh
Reviewed-By: Joyee Cheung joyeec9h3@gmail.com
Reviewed-By: Richard Lau richard.lau@ibm.com
Reviewed-By: Ulises Gascón ulisesgascongonzalez@gmail.com
Reviewed-By: James M Snell jasnell@gmail.com
Reviewed-By: Mike McCready 66998419+MikeMcC399@users.noreply.github.com

This manual backport is needed because bcf5850 from #63737 does not cleanly backport. The width of the table https://github.com/nodejs/node/blob/main/BUILDING.md#platform-list in the main and v26.x branches is different.

Background

Ancestors in main branch need to be skipped for backporting to v26.x:

• c362db6 from build: downgrade Intel macOS support to experimental #65427 is semver-major
• 313b834 from build: bump RUSTC_VERSION to 1.88 in github workflows #65742 is marked dont-land-on-v26.x

Node.js does not support a platform version if a vendor has expired support for it.
The lowest Alpine Linux version supported is v3.21 according to https://alpinelinux.org/releases/, so
minimum versions are aligned to Alpine v3.21 and are bumped to:

kernel >= 6.12, musl >= 1.2.5

Documentation backport needed as reference for the support description in nodejs/docker-node for Alpine Linux x64 images. Docker documentation needs to move from describing these builds as "Experimental" to categorizing them as falling under "Tier 2" support - see musl builds for Alpine.

[nodejs-github-bot]

Review requested:

• @nodejs/build
• @nodejs/tsc

[sxa]

I'm happy to approve this, although typically changes will be ported automatically to v26.x when a release is done so this shouldn't need to be PRd explicitly.

[MikeMcC399]

I'm happy to approve this, although typically changes will be ported automatically to v26.x when a release is done so this shouldn't need to be PRd explicitly.

Thanks for the approval! I added a couple of lines to the PR text to describe that the table width changed due to other commits. The original commit does not backport cleanly and needs conflicts manually resolving.

[sxa]

That's true, although since c362db6 would also get pulled into the next v26.x release that should resolve itself :-)

[MikeMcC399]

That's true, although since c362db6 would also get pulled into the next v26.x release that should resolve itself :-)

I assumed that semver-major PRs that contain breaking changes and should be released in the next major version. meant it could only be backported to Node.js 27.x not Node.js 26.x.

In any case the motivation for the PR was to make sure that there were no unnecessary delays in getting this documentation change backported. If it turns out the backport PR was unnecessary, then the backporting team can certainly choose to close it as redundant.